Thank you.
I do not understand german, I tried apt-get update and I have the message:
-------------------------------------------
W: Failed to fetch http://mozilla.debian.net/dists/squeeze ... ts/Release Unable to find expected entry iceweasel-4.0/binary-amd64/Packages in Meta-index file (malformed Release file?)
E: Some index files failed to download, they have been ignored, or old ones used instead.
-------------------------------
What should I do?

perhaps you haven't the correct sources.lst
see !iceweasel in the IRC what the help-bot say.
Or you may ask the folks in the IRC there (English is no problem)

TheOne

Titel:Verfasst am: 29.08.2011, 22:36 Uhr

Anmeldung: 15. Mar 2008
Beiträge: 610

IIRC the iceweasel source list entry of last ISO is unfortunately inside of /etc/apt/sources.list instead of a separate source list entry as /etc/apt/sources.list.d/iceweasel.list. That's why you should update the general sources.list file as well. See !hellfire point 1 in IRC too.